2,150 Works

Dynamic simulation of different transport options of renewable hydrogen to a refinery in a coupled energy system approach

Lisa Andresen, Carsten Bode & Gerhard Schmitz
Three alternative transport options for hydrogen generated from excess renewable power to a refinery of different scales are compared to the reference case by means of hydrogen production cost, overall efficiency, and CO2 emissions. The hydrogen is transported by a) the natural gas grid and reclaimed by the existing steam reformer, b) an own pipeline and c) hydrogen trailers. The analysis is applied to the city of Hamburg, Germany, for two scenarios of installed renewable...

Implementation of earthworm-assisted constructed wetlands to treat wastewater and possibility of using alternative plants in constructed wetlands

Nathasith Chiarawatchai
The aim of this research was to add the earthworms into the constructed wetlands, both in Germany and Thailand, in order to investigate whether they could improve the treatment performances. For Germany, earthworm-assisted constructed wetlands exhibited better treatment efficiency than conventional vertical subsurface-flow constructed wetlands and the unplanted constructed wetlands with earthworms. For Thailand, the production of sludge on the surface of wetlands was reduced by 40% with earthworms. Apart from that, alternative plants with...

The innovation process: an introduction to process models

Birgit Verworn & Cornelius Herstatt
In research as well as in practice, process models are an expatiated element of innovation management. They fulfill different tasks. In practice, for instance, process models are used as a management tool to standardize development activities. Researchers try to identify activities to be found in every product development process. The design of the different process models is as manifold as their application. It heavily depends on the intention of the practitioner or academic. Therefore, there...

Über die Ermittlung hydrodynamischer Kräfte aus Impuls- und Energieansätzen

Klaus Eggers
Über die Ermittlung hydrodynamischer Kräfte aus Impuls- und Energieansätzen

Low-tech sustainable sanitation options for Ghana and Ethiopia – economic, social and technical aspects

Aleksandra Drewko
Ecological sanitation (ecosan) is analyzed from a holistic system’s perspective on the example of two case studies. In the case study Ethiopia, a business idea for the production of plastic toilet slabs applicable under the ecosan approach is drafted. In the case study Ghana, an economic analysis of building or modifying toilets for the separate collection of urine and feces, transportation of urine to its storage locations, urine storage and subsequently selling it to farmers...

Solving regularized total least squares problems based on eigenproblems

Jörg Lampe
In the first part of the thesis we review basic knowledge of regularized least squares problems and present a significant acceleration of an existing method for the solution of trust-region problems. In the second part we present the basic theory of total least squares (TLS) problems and give an overview of possible extensions. Regularization of TLS problems by truncation and bidiagonalization approaches are briefly covered. Several approaches for solving the Tikhonov TLS problem based on...

Lernen, Informationskompetenz und Visualisierung - das Online-Tutorial DISCUS (Developing Information Skills & Competence for University Students) der Universitätsbibliothek der TU Hamburg-Harburg

Detlev Bieler, Thomas Hapke & Oliver Marahrens
Über effiziente Recherche - und Navigationsstrategien hinaus umfasst Informationskompetenz vor allem die Kreativität, den eigenen Informationsprozess bewusst und bedarfsgerecht zu gestalten. Um diverse Zielgruppen und Lerntypen zu erreichen, ist ein weites Spektrum an Aktivitäten zur Informationskompetenz-Förderung - von vollständigen Curricula bis hin zu Lernobjekten - durch Bibliotheken wünschenswert. Der explorative und eher spielerische Ansatz des zweisprachigen Online-Tutorials DISCUS (Developing Information Skills & Competence for University Students) der Universitätsbibliothek der TU Hamburg-Harburg findet seine Entsprechung im...

Maximizing the fixation strength of modular components by impaction without tissue damage

Annika Krull, Michael M. Morlock & Nicholas E. Bishop
Taper junctions between modular hip arthroplasty femoral heads and stems fail by wear or corrosion which can be caused by relative motion at their interface. Increasing the assembly force can reduce relative motion and corrosion but may also damage surrounding tissues. The purpose of this study was to determine the effects of increasing the impaction energy and the stiffness of the impactor tool on the stability of the taper junction and on the forces transmitted...

Zuverlässigkeit von keramischen Mehrlagensubstraten

Niko Sebastian Dorsch
Ein Zuverlässigkeitsmodell für Dickschichtwiderstände wird vorgestellt, welches die Widerstandsänderung aufgrund wachsender Mikrorisse beschreibt. Die zeitabhängige Ausfallwahrscheinlichkeit wird unter Beachtung statistisch streuender Eingangsparameter berechnet. Gezeigt werden die Berechnungsprozedur, eine Finite-Elemente-Risswachstumsberechnung, Methoden zur Charakterisierung von Dickschichtmaterialien und ein Verifikationsexperiment. Die Ausfallwahrscheinlichkeit aktueller Dickschichtwiderstände ist vernachlässigbar klein.

Rechnerische Bestimmung der Widerstandserhöhung eines Schiffes in regelmäßigen Wellen und Vergleich mit entsprechenden Modellversuchen

Peter Blume, Ullrich Keil & Peter Schenzle
Die mittlere Erhöhung des Widerstandes eines Schiffes im Seegang ist bei Kenntnis des Seeganges und der Übertragungsfunktionen der Vertikal- und Relativbewegung des Schiffes vorhersagbar über die Berechnung der Übertragungsfunktion für die Widerstands erhöhung in regelmäßigen Wellen. Der Vergleich von Versuchsergebnissen, mit entsprechenden Rechnungen läßt eine gute übereinstimmung im Bereich der Maximalwerte erkennen. Es zeigt sich deutlich, daß diese Maxima für den Fall Wellehlänge = Schiffslänge zu erwarten sind.

TUHH Spektrum Sommersemester 2002

Präsident Der Technischen Universität Hamburg-Harburg
Ultraschall in der Umwelttechnik, 20 Jahre Arbeitsbereich Umweltschutztechnik, Energie aus Biomasse, Fernerkundungssystem zur Messung gefährlicher Chemikalien in der Luft, E-Learning in der Produktionstechnik, Wohnen in Winsen (Luhe), Bodenmechanisches Praktikum, Arbeitsgruppe Humanities, AStA

Influence of finite notch root radius and optically determined crack length on the measured fracture toughness of brittle materials

Hüseyin Özcoban, Hans Jelitto & Gerold A. Schneider
When measuring the fracture toughness of ceramics, for instance with the Single Edge V-Notched Beam (SEVNB) method, a known problem is given by the finite notch root radius. If this radius is larger than a certain small value of a few micrometers, the measured stress intensity factor is higher than the true intrinsic value. Another problem is that due to technical and physical reasons the optically measured crack length at stable crack growth is smaller...

Determining periodic orbits via nonlinear filtering and recurrence spectra in the presence of noise

Sebastian Oberst, Steffen Marburg & Norbert Hoffmann
In nonlinear dynamical systems the determination of stable and unstable periodic orbits as part of phase space prediction is problematic in particular if perturbed by noise. Fourier spectra of the time series or its autocorrelation function have shown to be of little use if the dynamic process is not strictly wide-sense stationary or if it is nonlinear. To locate unstable periodic orbits of a chaotic attractor in phase space the least stable eigenvalue can be...

Three-Dimensional Internal Gravity Waves in a Stratifield Free-Surface Flow

Theodore Yao-Tsu Wu
Three-Dimensional Internal Gravity Waves in a Stratifield Free-Surface Flow

Settlements in unsaturated granular soils induced by changes in saturation and suction

Marius Milatz, Tom Törzs & Jürgen Grabe
In this contribution the hydro-mechanically coupled behaviour of a sand is experimentally investigated with the focus on settlements induced by changes in degree of saturation and suction. This phenomenon, referred to as collapse behaviour, is attributed to rearrangements of the grain skeleton due to changing capillary effects on wetting of the soil. For the experimental investigation of the collapse behaviour of a medium coarse sand cyclic dryingwetting tests are performed under oedometric conditions. In the...

Stabilization of dredged sludge by chemically and mineralogically different additives

Reza Khorasani, Wolfgang Calmano & Ulrich Förstner
Sludge from the harbour of Hamburg which was highly contaminated with heavy metals and organic toxicants has been stabilized by means of lime, calcium hydroxide, calcium carbonate, gypsum, trass, waste kiln dust, cement, coal fly ash and, red mud. Analysis of the solidification products by polarization microscope, electron microscope, X-ray diffraction, electron microprobe, and proton-induced X-ray emission microprobe (PIXE) indicates that new minerals have been formed. These new mineral formations stabilize the material and change,...

Coupled chemo(enzymatic) reactions in continuous flow

Ruslan Yuryev, Simon Strompen & Andreas Liese
This review highlights the state of the art in the field of coupled chemo(enzymatic) reactions in continuous flow. Three different approaches to such reaction systems are presented herein and discussed in view of their advantages and disadvantages as well as trends for their future development.

On the stability of the evolution Galerkin schemes applied to a two-dimensional wave equations system

Mária Medviďová-Lukáčová, Gerald Warnecke & Yousef Zahaykah
The subject of the paper is the analysis of stability of the evolution Galerkin (EG) methods for the two-dimensional wave equation system. We apply von Neumann analysis and use the Fourier transformation to estimate the stability limits of both the first and the second order EG methods.

A model-order reduction technique for low rank rational perturbations of linear eigenproblems

Heinrich Voß & Frank Blömeling
Large and sparse rational eigenproblems where the rational term is of low rank k arise in vibrations of fluid–solid structures and of plates with elastically attached loads. Exploiting model order reduction techniques, namely the Pad´e approximation via block Lanczos method, problems of this type can be reduced to k–dimensional rational eigenproblems which can be solved efficiently by safeguarded iteration.

Temperature-dependent synchrotron powder diffraction phase studies of (K0.37Na0.52Li0.03)(Nb0.87Ta0.1Sb0.03)O3 ferroelectric ceramics

Henry Ekene Mgbemere, Rodrigo P. Fernando, Manuel Hinterstein & Gerold A. Schneider
Temperature-dependent synchrotron powder diffraction measurements have been performed on leadfree ferroelectric (K0.37Na0.52Li0.03)(Nb0.87Ta0.1Sb0.03)O3 ceramics. The measurement was performed from 20 °C to 400 °C with 20 °C steps. The diffraction patterns showed the existence of two phases from 20 °C to 180 °C while the ferroelectric to paraelectric phase transition occurred between 340 °C and 360 °C. Rietveld refinement using the Fullprof software was employed and the two-phase region was refined using a combination of the...

Calibration and Verification of a Mathematical Model for the Simulation of Blackwater/Biowaste Digestion

Yucheng Feng
The object of this work is to apply and develop IWA anaerobic digestion model No.1 (ADM1) to the blackwater anaerobic digestion (BWAD) plant. The basic theory of anaerobic digestion (AD) processes and biochemical kinetics were introduced first. Afterwards the model was calibrated based on the performance of a lab-scale BWAD plant (at the mesophilic condition). The calculation includes three scenario studies, i.e. the reference conditions, the different feeding frequency and with high NH4+ input concentration....

Berechnung von Trossensystemen nach der Klaffungsmethode

Werner Blendermann
Berechnung von Trossensystemen nach der Klaffungsmethode

Existenz, Eindeutigkeit und Regularität stationärer Wellenströmungen, die von Druckverteilungen an der Wasseroberfläche verursacht werden

Andreas Gamst
Existenz, Eindeutigkeit und Regularität stationärer Wellenströmungen, die von Druckverteilungen an der Wasseroberfläche verursacht werden -Lineare Theorie-

Leistungsmerkmale eines KMU-gerechten Innovationsaudits - Beitrag zur Erarbeitung eines Hamburger Innovationsaudits

Cornelius Herstatt, Stephan Buse, Stefan Trapp & Christoph Stockstrom
Der unternehmerische Innovationserfolg ist nur bedingt planbar. Sieht man einmal von zufälligen Erfolgen ab, erfordert das Hervorbringen von innovativen Produkten, Prozessen und Dienstleistungen im Allgemeinen ein funktionierendes Innovationsmanagement. Dies gilt für Unternehmen jeder Größe. Mit der Hilfe von Innovationsaudits können Defizite im betrieblichen Innovationsmanagement eruiert und darauf abzielende Verbesserungsmaßnahmen ausgearbeitet und umgesetzt werden. Innovationsaudits leisten somit einerseits einen wichtigen Beitrag zur Beurteilung der Innovationsfähigkeit eines Unternehmens, andererseits zeigen sie die Richtungen zur Stärkung des Innovationssystems...

Size affected dislocation activity in crystals : advanced surface and grain boundary conditions

Edgar Husser, Celal Soyarslan & Swantje Bargmann
Extended crystal plasticity theories are well established to study size-dependent hardening of metals. Surface and inner grain boundary conditions play a significant role for crystals at small scales as they affect the dislocation activity and, hence, alter strength and strain hardening behavior. Conventional micro boundary conditions, i.e., microhard and microfree, are unable to capture the underlying physics as they describe ideal and over-simplified surface/interface conditions. In this work, advanced boundary conditions for gradient extended crystal...

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